动态第185页 - 绿手指 - 养花技巧、花生病了怎么办、花园打理和设计

2018年05月26日

Description: This perennial wildflower is up to 2½' tall and across. Its central stem (and any side stems) is pale green to pale purplish green, terete, glabrous, and glaucous. The alternate compound leaves are double or triple odd-pinnate, spanning up to 1' long and across. Each branch of a compound leaf has 3 or 5 leaflets; like the central stem, the branches of the compound leaves are pale green to pale purplish green, glabrous, and glaucous. Individual leaflets are up to 1¾" long and across; they are reniform-orbicular to oval-orbicular in shape with 3-9 terminal lobes (usually 5 or more). These short lobes are well-rounded or bluntly pointed. The upper surface of each leaf is medium green and smooth, while the lower surface is pale green with a conspicuous network of raised veins; both sides are hairless. All of the leaflets have slender petioles. The central stem terminates in a large floral panicle up to 1' tall and across; each branch of the panicle terminates in a corymb of about 5 flowers. Because Early Meadow Rue is dioecious, some plants produce all male (staminate) flowers, while other plants produce all female (pistillate) flowers. The male flowers droop downward from their branches to a greater extent than the female flowers. Each male flower is about ¼" across and ½" long; it consists of 4-5 sepals and 10 or more stamens. The sepals are broadly oblong, pale green, light-veined, and white-margined; the stamens have long yellow anthers and slender filaments. Each female flower is about the same size as the male flower; it consists of 4-5 sepals and up to 15 pistils. The sepals are similar to those of the male flowers, while the pistils are grey with flat-sided styles. Neither male nor female flowers have petals. The blooming period occurs from mid- to late spring. Cross-pollination is by wind and there is no floral fragrance. The male flowers soon wither away, while the fertile female flowers are replaced by ellipsoid achenes that are pointed at both ends and strongly ribbed. After flowering plants die down during the summer, low basal leaves develop during the fall. Their appearance is similar to the alternate compound leaves, as described above. The root system is fibrous and rhizomatous. This wildflower can reproduce by its rhizomes or achenes. [图片]Cultivation: The preference is light shade, mesic conditions, and a loam or clay-loam soil. Most vegetative growth occurs during the spring and early summer. Range & Habitat: The native Early Meadow Rue is occasional in eastern central and northern Illinois, but it is uncommon or absent elsewhere in the state (see Distribution Map). Habitats include rich mesic woodlands, wooded clay slopes, shaded areas near cliffs, and rocky ravines. In Illinois, this species is typically found in Maple-Basswood woodlands. It blooms before the canopy trees have fully developed their leaves. Faunal Associations: The caterpillars of the following Noctuid moths feed on Thalictrum spp. (Meadow Rue species) – Calyptra canadensis (Canadian Owlet), Papaipema unimoda (Borer Moth sp.), and Pseudeva purpurigera (Straight-Lined Looper Moth). White-Tailed Deer browse on the foliage of Early Meadow Rue sparingly. [图片]Photographic Location: A mesic woodland in east-central Illinois. The photographed plant is staminate (male). Comments: Early Meadow Rue is shorter in stature and blooms earlier than other Thalictrum spp. in Illinois. It also has greater fidelity to shady woodlands as a habitat. All of these species have elegant foliage and unusual wind-pollinated flowers. The male flowers of Early Meadow Rue are more showy than the female flowers; this is primarily because the anthers of the male flowers are yellow, while the styles of the female flowers are dull-colored. The leaflets of Early Meadow Rue have more terminal lobes (usually 5-9) than the leaflets of other Thalictrum spp. in the state (usually 3-5). Because of this distinctive characteristic, it is easy to identify.

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Miss Chen

2018年05月26日

Description: This herbaceous perennial plant is 2–3½' tall, branching occasionally in the upper half. It is more or less erect, although the weight of the inflorescence often causes the entire plant to lean sideways. The slender stems are light green, terete, and either glabrous, sparsely pubescent, or hairy in lines. The alternate leaves are up to 6" long and 2" across, becoming gradually smaller as they ascend the stems. The petioles are very slender and about 1" long on the lower leaves, while the upper leaves are nearly sessile. The petioles are light green and often hairy. The lower to middle leaves are lanceolate-ovate with indented bases, while the upper leaves are lanceolate with rounded bases. All leaves taper gradually into slender acute tips, while their margins are smooth and often slightly ciliate. The upper leaf surface is medium green and glabrous (or nearly so), while the lower leaf surface is light green and either sparsely pubescent, hairy along the central vein, or glabrous. The lower leaf surface also has a reticulated network of fine secondary veins. The central stem (and any upper lateral stems) terminates in a panicle of flowerheads up to 1½' long and ¾' across. Each flowerhead is about ¾–1" across, consisting of 10-20 ray florets that surround a similar number of disk florets. The petaloid rays of these flowerheads are lavender or pale blue-violet (rarely white), and they are individually linear-oblong in shape. The corollas of the disk florets are short-tubular with 5 minute lobes at their apices. Initially, these corollas are yellow, but they become reddish purple with age. On unusual specimens, these corollas are light pink to nearly white. At the base of each flowerhead, the overlapping phyllaries (scaly floral bracts) are linear-lanceolate and glabrous to finely pubescent. Depending on the stage of their maturity, the phyllaries have patches of dark green that are diamond-shaped near their tips, or they have central veins that are dark green. Otherwise, the phyllaries are light green. The blooming period occurs from late summer through the fall, lasting about 1–1½ months. Both the ray and disk florets can produce fertile achenes. These achenes are 2-3 mm. long and oblongoid in shape; they have small tufts of light brown hair at their apices. As a result, the achenes are distributed primarily by the wind. The root system is fibrous and rhizomatous; older plants sometimes develop a small caudex. Clonal colonies of plants can develop from the rhizomes. [图片]Cultivation: The preference is partial sun, mesic to dry-mesic conditions, and soil that contains loam or some rocky material with decaying organic matter. Calcareous ground with a higher than normal pH is tolerated. Like many other asters (Symphyotrichum spp.), the foliage can be attacked by many kinds of insects and disease organisms. The plants have a tendency to flop over while in bloom. Range & Habitat: The native Short's Aster is a fairly common species that occurs in the majority of counties in Illinois. However, it is less common in some southern areas of the state (see Distribution Map). Habitats include mesic to upland woodlands, rocky open woodlands and slopes, limestone bluffs, woodland borders, and areas along woodland paths. Short's Aster occurs in both oak-hickory woodlands and maple-basswood woodlands. This aster often occurs in areas where limestone is close to the surface of the ground; it is usually found in higher quality natural areas. Wildfires and other kinds of disturbance can be beneficial if they reduce excessive shade from overhead canopy trees, or they reduce competition from invasive shrubs. [图片]Faunal Associations: The flowerheads of asters (Symphyotrichum spp.) attract many kinds of insects, especially long-tongued bees, small-tongued bees, butterflies, skippers, and flies. These insects obtain nectar or pollen from the flowerheads. Some bees are specialist pollinators of asters and sometimes goldenrods (Solidago spp.); these species include the plasterer bee Colletes simulans armata, and such Andrenid bees as Andrena asteris, Andrena asteroides, Andrena hirticincta, Andrena nubecula, Andrena simplex, and Andrena solidaginis. The caterpillars of two butterflies, Chlosyne nycteis (Silvery Checkerspot) and Phyciodes tharos (Pearl Crescent), feed on the foliage of asters. In addition, the caterpillars of such moths as Cucullia asteroides (The Asteroid), Carmenta corni (Aster Borer Moth), and many others feed on various parts of asters (see Moth Table). Other insect feeders include Exema canadensis and other leaf beetles, larvae of Calycomyza humeralis (Aster Leafminer Fly), larvae of several fruit flies, many aphids (especially Uroleucon spp.), Macrosteles fascifrons (Aster Leafhopper), the plant bug Plagiognathus cuneatus, and Corythucha marmorata (Goldenrod Lace Bug). Among birds, the Wild Turkey and Ruffed Grouse occasionally eat the seeds and foliage of these plants in woodland areas. Among mammals, both the White-tailed Deer and Cottontail Rabbit undoubtedly feed on the rather smooth foliage of Short's Aster and similar asters. [图片]Photographic Location: A woodland edge near Busey Woods in Urbana, Illinois. Comments: This is one of the more attractive woodland asters with flowers that are larger than average in size. Short's Aster (Symphyotrichum shortii) can be distinguished from other asters (Symphyotrichum spp.) by carefully considering the appearance of the foliage and flowerheads. The lower to middle leaves of Short's Aster are indented at the base with narrow petioles. Some asters, such as Symphyotrichum sagittifolium (Arrow-Leaved Aster), have winged petioles on their lower to middle leaves, while other asters have rounded or wedge-shaped bases on their lower to middle leaves. The margins of leaves in Short's Aster are devoid of teeth (or nearly so), while other woodland asters, such as Symphyotrichum cordifolium (Blue Wood Aster), have leaf margins with conspicuous teeth. Similarly, the upper leaf surface in Short's Aster is hairless (or nearly so), while the upper leaf surface of Symphyotrichum drummondii (Drummond's Aster) is pubescent. Finally, the flowerheads of Short's Aster are usually ¾" across or more, while the flowerheads of other woodland asters are usually less than ¾" across. A scientific synonym of this species is Aster shortii.

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Miss Chen

2018年05月26日

Description: This perennial wildflower is 2-3½' tall, sending up one or more leafy stems during the late spring. Initially, these stems are erect to ascending, but later in the year they sometimes sprawl across the ground. These stems are unbranched below and occasionally branched above; they are light green to reddish brown, terete, glabrous below, and lined with short hairs above. The alternate leaves are up to 4" long and 2½" across, becoming smaller as they ascend the stems. The lower leaves are cordate to cordate-ovate in shape and coarsely serrated to crenate-serrate along their margins. The upper leaves are cordate-ovate to ovate in shape and crenate-serrate to slightly crenate-serrate along their margins. The petioles are up to one-half the length of the blades, becoming relatively shorter as they ascend the stems; these petioles are conspicuously winged along their margins and they are often ciliate or slightly pubescent. The upper surfaces of the leaves are glabrous to sparsely covered with short hairs, while their lower surfaces are usually glabrous, except for some fine hairs along the major veins. However, some young leaves may have sparse short-pubescence on their lower surfaces. The central stem and upper lateral stems (if any) terminate in panicles of flowerheads that are ¾-1¾' long and about one-half as much across. The lateral branches of these panicles are ascending; the peduncles of the flowerheads are short (up to ½" in length). The central stalk, lateral branches, and peduncles are light green to reddish brown, terete, and either glabrous, short-pubescent, or lined with short hairs. Each flowerhead is about ½" across, consisting of about 8-15 ray florets that surround 8-12 disk florets. The petaloid rays of the flowerheads are lavender, light blue-violet, or white. The corollas of the disk florets are initially cream-colored or yellow, but they later become reddish purple. Around the base of each flowerhead, there are phyllaries (scale-like floral bracts) in several overlapping series; individual phyllaries are 2-5 mm. in length. Individual phyllaries are linear-lanceolate to narrowly lanceolate, appressed together or slightly spreading, and they have dark green patches near their tips that are diamond-shaped. Leafy bracts up to 1" long occur along the central stalks and lateral branches of panicles; they are linear-oblong or elliptic in shape and entire (smooth) along their margins. The blooming period occurs from late summer into the autumn and lasts about 1-3 months. Afterwards, the florets are replaced by achenes with small tufts of hair; they are distributed by the wind. The achenes are 2.0-2.5 mm. long, oblongoid-oblanceoloid in shape, and brown to purplish brown. The root system is fibrous and short-rhizomatous; an older plant may develop a small woody caudex. This wildflower spreads by reseeding itself and by forming clonal offsets from the rhizomes. A rosette of semi-evergreen basal leaves is created during the autumn that can persist until the spring. These basal leaves are ¾-3" long, cordate-ovate in shape, and crenate-serrated along their margins. Their upper surfaces are medium green and glabrous, while their lower surfaces are pale green and glabrous to finely hairy along the major veins. The petioles are about the same length as the corresponding basal leaves; they are narrow or slightly winged. [图片]Cultivation: The preference is partial sun, mesic to dry conditions, and soil that contains loam, clay-loam, or rocky-loam. The leaves may become yellowish green when they are exposed to bright sunlight; the lower leaves may become wilted and fall off their stems during hot dry weather. Sometimes powdery mildew attacks the leaves during the late summer or fall when moisture is abundant. Range & Habitat: The native Arrow-Leaved Aster is common in most areas of Illinois, except some counties in the south-central area of the state (see Distribution Map). Habitats include upland woodlands, rocky woodlands, wooded slopes, thinly wooded bluffs, woodland edges, savannas, rocky glades, grassy thickets, small meadows in wooded areas, and edges of yards. This aster tolerates disturbance to some extent. [图片]Faunal Associations: The nectar and pollen of the flowerheads attract many kinds of insects, including long-tongued bees, short-tongued bees, Syrphid flies, bee flies, wasps, and occasional butterflies or skippers. Caterpillars of the butterflies Chlosyne nycteis (Silvery Checkerspot) and Phyciodes tharos (Pearl Crescent) feed on the foliage of asters (Symphyotrichum spp.), while the caterpillars of many moths feed on the foliage, flowerheads, developing seeds, stems, or roots (see Moth Table). Other insect feeders include leaf beetles, lace bugs, plant bugs, stink bugs, aphids, leafhoppers, and the larvae of leaf-mining flies and fruit flies (see Insect Table for a list of these species). Among vertebrate animals, the Wild Turkey and Ruffed Grouse occasionally eat the seeds and young foliage of asters, while such mammalian herbivores as deer, rabbits, groundhogs, and livestock browse on the foliage. Photographic Location: Border of a wooded area at Crystal Lake Park in Urbana, Illinois. [图片]Comments: Arrow-Leaved Aster (Symphyotrichum sagittifolium) is one of several woodland asters with relatively small flowerheads that have cordate or cordate-ovate lower leaves. While the leaves can become rather coarse, the panicles of abundant flowerheads are often showy. This species has an appearance that is similar to Drummond's Aster (Symphyotrichum drummondii), Heart-Leaved Aster (Symphyotrichum cordifolium), and White Arrowleaf Aster (Symphyotrichum urophyllum), which occur in similar habitats. Drummond's Aster has stems and leaf undersides that are evenly pubescent, while the stems of Arrow-Leaved Aster are either glabrous or they are lined with hairs, and the undersides of its leaves are either glabrous or they have fine hairs along the major veins. Heart-Leaved Aster can be distinguished by the narrow petioles of its alternate leaves, while those of Arrow-Leaved Aster are conspicuously winged. Sometimes the latter is considered a variety of Heart-Leaved Aster, or Symphyotrichum cordifolium sagittifolium (Jones, 1989). Finally, Arrow-Leaved Aster and White Arrowleaf Aster are regarded as the same species by some authorities (e.g., efloras, USDA, and ITIS), while Mohlenbrock (2014) considers them to be distinct. An argument for the latter point-of-view can be made as, compared to Arrow-Leaved Aster, White Arrowleaf Aster has more narrow upper leaves (typically ovate to lanceolate), the margins of its leaves are less strongly toothed or they lack teeth, and its phyllaries have green central stripes, rather than diamond-shaped patches of dark green toward their tips. In addition, the petaloid rays of this latter aster are almost always white. All species in this complex of asters were assigned orginally to the Aster genus.

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Miss Chen

2018年05月26日

Description: This perennial wildflower is 1½–3' tall. Each plant has a central stem that develops from the rootstock (less often, there are 2-3 such stems), which branches from below the middle. During the flowering period, short secondary stems develop from the axils of the leaves. These stems are terete, mostly light green, and pubescent; sometimes they have longitudinal ridges. The alternate leaves are up to 3½" long and 1" across; they are lanceolate, oblanceolate, or narrowly ovate with margins that are slightly toothed or smooth. The upper surface of each leaf is medium green and hairless, while the lower surface is light green and finely short-pubescent. Sometimes there are longer hairs along the central vein on the underside of each leaf. The leaves are sessile against their stems and their outer tips are somewhat blunt. The upper stems terminate in elongated panicles of flowerheads. Each flowerhead spans about ½" across, consisting of 15-25 white ray florets and a similar number of disk florets. The disk florets are initially pale yellow, but they later become reddish purple; each disk floret is tubular in shape with 5 spreading lobes along its upper rim. Surrounding the base of each flowerhead, there is an overlapping series of small floral bracts (phyllaries). These floral bracts are linear in shape, evenly green from top to bottom, and appressed or slightly spreading. Each flowerhead has a short peduncle up to 1" long. In addition to the flowerheads, the branches of the panicle have numerous leafy bracts. These leafy bracts are similar in appearance to the leaves, except smaller in size. The blooming period occurs from late summer into the fall and lasts about 1-2 months. Each flowerhead is replaced by a dense cluster of small achenes. Each achene is bullet-shaped with a small tuft of white hairs at its apex. The achenes are distributed by the wind. The root system is fibrous and long-rhizomatous. Small colonies of plants are occasionally formed. Cultivation: The preference is partial or dappled sunlight, moist to mesic conditions, and a fertile loamy soil. Other kinds of soil are also tolerated. [图片]Range & Habitat: The native Ontario Aster is occasional to locally common throughout Illinois (see Distribution Map). Habitats include open woodlands, woodland openings, woodland borders, partially shaded cliffs, areas along woodland paths, powerline clearances in wooded areas, low areas along woodland streams, savannas, moist meadows, and abandoned fields. This aster benefits from disturbance if it reduces excessive shade from canopy trees. Faunal Associations: The nectar and/or pollen attract various insects, including bumblebees, little carpenter bees (Ceratina spp.), leaf-cutting bees (Megachile spp.), Halictid bees, Syrphid flies, and butterflies. A long-horned bee, Melissodes dentriventris, is an oligolectic floral visitor of this and other asters (Symphyotrichum spp.). These insects cross-pollinate the flowers. Other insects, including aphids, plant bugs, leaf beetles, etc., feed destructively on asters (see Insect Table); there are also a large number of moth caterpillars that feed on various parts of asters (see Moth Table). The Ruffed Grouse and Wild Turkey feed on the leaves and seeds of these plants to a limited extent; White-Tailed Deer and Cottontail Rabbits also feed on the foliage to a limited extent. Photographic Location: A powerline clearance at Busey Woods in Urbana, Illinois. Comments: This aster has a rather ordinary appearance and it is often omitted in many wildflower guides. Ontario Aster (Symphyotrichum ontarionis) resembles several other asters (Symphyotrichum spp.) with small white flowerheads and they often occur in the same or similar habitats. In general, Ontario Aster can be distinguished from these other species by the even pubescence of its stems and the even canescence (short fine pubescence) on the underside of its leaves. Other similar asters have stems with lines of hair and the undersides of their leaves are either hairy along the major veins or hairless. The flowerheads of Ontario Aster have 15-25 ray florets and its floral bracts are evenly green from top to bottom. Other similar asters have fewer ray florets (10-15) or their floral bracts have a diamond-shaped pattern near their tips that is dark green. Ontario Aster also has an abundance of leafy green bracts along the branches of its panicles, while the bracts of other asters are smaller in size and more scale-like in appearance. Sometimes Ontario Aster hybridizes with similar species of asters, which increases the difficulty of identification. A scientific synonym of this species is Aster ontarionis.

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Miss Chen

2018年05月26日

Description: This perennial wildflower consists of a small rosette of basal leaves about 3-8" across, persisting from autumn to spring. These basal leaves are semi-evergreen, ¾-2½" long, and ½-2" across; they are oval-cordate in shape and their margins are crenate-serrate. The upper surfaces of basal leaves are medium green and sparsely to moderately short-pubescent, while their lower surfaces are light green and moderately to densely short-pubescent. Exposure to near-freezing temperatures sometimes causes the basal leaves to turn purple. The petioles of basal leaves are up to 2" long, slender, and short-pubescent. This wildflower bolts during the late spring to produce one or more leafy stems about 1½-3¼' long that are initially erect or ascending, although tending to sprawl across the ground later in the year. These stems are light green to purple, terete, and short-pubescent to pubescent throughout; this pubescence is not restricted to longitudinal lines. The stems are unbranched below, while they are sparingly to occasionally branched above. Alternate leaves occur along these stems that are 1-4" long and ½-3" across (becoming smaller in size as they ascend the stems); they are cordate below, becoming cordate-ovate to lanceolate above. The margins of these alternate leaves are coarsely serrated below, becoming serrated to slightly crenate-serrate above. The upper surfaces of these leaves are moderate green and sparsely short-pubescent to densely short-pubescent, while their lower surfaces are light green and moderately to densely short-pubescent or pubescent throughout; this pubescence is not restricted to the major veins. When these leaves are exposed to bright sunlight, they may become yellowish green. Leaf texture tends to be stiff and rough. The petioles of alternate leaves are ½-2" long and their margins are more or less winged; they are moderately to densely short-pubescent. Sometimes small secondary leaves appear in the axils of these leaves. Each leafy stem terminates in a panicle of flowerheads about ½-2' long and about one-half as much across. In addition to the central stalk of the panicle, there are several ascending lateral branches along which most of the flowerheads occur on short peduncles (less than ½" long). The central stalk, branches and peduncles are light green to purple, terete, and evenly short-pubescent to pubescent. [图片]Each flowerhead is about ½" across, consisting of 10-15 ray florets that surround 10-15 congested disk florets. The petaloid rays of these flowerheads are usually lavender or light violet (less often white) and linear-oblong in shape. The short-tubular disk florets are initially cream-colored to yellow, but they later become reddish purple. Each disk floret has 5 short lobes that are erect. Around the base of each flowerhead, the scale-like phyllaries (floral bracts) are arranged in several overlapping series; these phyllaries are appressed together, or nearly so. Individual phyllaries are 4-6 mm. in length, linear-lanceolate in shape, and light green, except for diamond-shaped patches of dark green near their apices. Leafy bracts occur along central stalk and lateral branches of the panicle that are up to 1" long and elliptic to linear-oblong in shape; they are slightly toothed to entire (smooth) along their margins. The blooming period occurs from late summer into autumn for 1-3 months. Afterwards, the florets are replaced by achenes with small tufts of white hair. The achenes are 2-3 mm. long, oblongoid-oblanceoloid in shape, slightly ribbed, and light to medium brown (sometimes with reddish or purplish tints). They are distributed by the wind. The root system is fibrous and short-rhizomatous. On older plants, a small woody caudex may develop. Clonal offsets are often produced from the rhizomes. [图片]Cultivation: The preference is partial sun, mesic to dry-mesic conditions, and soil containing loam, clay-loam, or some rocky material. This wildflower is usually easy to cultivate. The foliage may become discolored with age; lower leaves may wither away in response to hot dry conditions. There is a tendency for the flowering stems to sprawl across the ground during the autumn. Range & Habitat: The native Drummond's Aster is common in central and northern Illinois, while in the southern section of the state it is occasional to locally common (see Distribution Map). Habitats include upland woodlands, rocky woodlands, woodland openings, woodland borders, areas along woodland paths, disturbed open woodlands, upland savannas, thinly wooded bluffs, powerline clearances through wooded areas, thickets, partially shaded riverbanks, burnt-over vacant lots, edges of yards, and partially shaded areas along roadsides. Drummond's Aster can be found in both high quality natural areas and degraded sites. Occasional wildfires are beneficial when they reduce excessive shade from overhead canopy trees. The woodlands where this aster occurs are dominated by various deciduous trees, especially oaks (Quercus spp.). [图片]Faunal Associations: The flowers are cross-pollinated by honeybees, bumblebees, Halictid bees (including green metallic bees), Andrenid bees, miscellaneous wasps, Syrphid flies, Tachinid flies, Muscid flies, butterflies, skippers, moths, and other insects. Both nectar and pollen are available as floral awards to such visitors. The following bees are oligolectic visitors (pollinator specialists) of aster flowers: Andrena asteris, Andrena asteroides, Andrena hirticincta, Andrena nubecula, Andrena solidaginis, and Colletes simulans armata. Some of these oligoleges also visit goldenrod flowers. Other insects that are associated with Drummond's Aster and other asters (Symphyotrichum spp.) include leaf beetles, larvae of fruit flies and leaf-mining flies, plant bugs, lace bugs, stink bugs, aphids, leafhoppers, walkingsticks, caterpillars of butterflies, and caterpillars of many moths. These insects feed destructively on the leaves, flowers, developing seeds, stems, roots, or plant juices (see the Insect Table and Moth Table for more information about these species). In general, asters are less important to vertebrate animals. However, such upland gamebirds as the Ruffed Grouse and Wild Turkey feed occasionally on the foliage and seeds; such mammals as deer, rabbits, groundhogs, and livestock also feed on the foliage. [图片]Photographic Location: Edge of a wooded area at Crystal Lake Park in Urbana, Illinois. Comments: Drummond's Aster (Symphyotrichum drummondii) is part of a complex of similar species involving Arrow-Leaved Aster (Symphyotrichum sagittifolium), Heart-leaved Aster (Symphyotrichum cordifolium), and White Arrowleaf Aster (Symphyotrichum urophyllum). There has been a history of taxonomic instability involving the interrelationships between these 4 species. Some of these species are considered varieties of each other by some taxonomists, or they have been merged with other species within this complex. Drummond's Aster can be distinguished from other species (or varieties) in this complex by the evenly distributed pubescence along its stems and by the evenly distributed pubescence on the lower sides of its leaves. The abundance and conspicuousness of this pubescence can vary across different populations of plants in Illinois. Drummond's Aster also differs from Heart-leaved Aster by its winged petioles; this is a trait that it shares with the remaining species of this complex. Relatively recently, all of these species have been assigned to the Symphyotrichum genus; Drummond's Aster was referred to previously as Aster drummondii. While the individual flowerheads are relatively small, the inflorescence of this aster is often quite large and showy during the autumn.

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Miss Chen

2018年05月26日

苏粉蚧别名柑桔臀纹粉蚧、柑桔粉炒。该虫食性杂，牡丹、菊花、十字景天、柑桔、棕榈等多种药用植物及果树均可受其害。成、若虫群集在嫩梢吸食汁液，造成梢叶枯萎或畸形早落，有时诱发煤污病。分布辽宁、山西、山东、江苏、上海、浙江、福建、湖北、广东、四川等省。北方主要发生在温室。 [图片]寄主牡丹、菊花、茶花、君子兰、风仙花、常春藤、十字景天、变叶木、柑桔、棕榈等多种药用植物及果树。为害特点成、若虫群集在嫩梢吸食汁液，造成梢叶枯萎或畸形早落，有时诱发煤污病。形态特征雌成虫体长2．5mm，黄褐色至青灰色，椭圆形，上被白蜡粉。体四周有白色蜡丝18对，尾端长。触角8节。后期背部显现出1条青灰色纵纹。雄成虫体长1．6mm，触角9节，眼红色，体被白蜡粉，体末有白色蜡丝2根。卵长0.3mm，椭圆形，初浅黄色，后变橙黄色。若虫共3龄。3龄若虫体长1．1mm，周缘的18对蜡丝已形成，触角7节。雄蛹长1．1mm，橙色，眼红色。茧椭圆形，白色。生活习性上海温室内年生3代，以受精雌成虫和部分带卵囊成虫于顶梢处或枝干分权处、裂缝中越冬。翌年4月中旬开始产卵，4月下旬?5月上旬进入产卵盛期，第1代若虫于4月中旬一6月下旬出现，1代雌成虫于5月下旬始见，6月中、下旬进入羽化盛期。2代以后发生期不整齐，至11月中下旬开始越冬。 [图片]防治方法 (1)加强检疫，防止该虫进入药圃或药园。 (2)加强管理，注意通风透光，防止该虫大量繁殖。 (3)必要时用40％乐果乳油1000倍液灌根有效。

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Miss Chen

2018年05月26日

美人蕉正如它的名字一样，它是一种很美的观花植物，叶似芭蕉、花朵儿似蝴蝶甚是娇艳而且花期还不短。近几年各地庭园、路旁栽植的杂种美人蕉、株型矮壮、叶色墨绿，花色丰富，色彩鲜艳，深为人们喜爱。可是1998年深圳绿地大片发生毁灭性青枯病。各地每年损失近10万株，病区发病率20~30%，严重的成片死亡，影响景观。 [图片]病菌侵染植株的茎干和根系，流行期植株从染病到枯死一般10~15天。大多从根部感病，也有从茎干处侵入，病株地上部叶片失水变黄，萎蔫下垂，逐渐茎基或茎干出现黑色条斑，绕茎一周后整株枯死。横切坏死根或茎，几分钟后切面上有乳白色或黄褐色细菌粘液溢出，此即为病原细菌，是室外诊断青枯病的重要依据。若纵切茎干还可见条状黑褐色斑带。发生规律：病菌可存活于土壤、植株残体和垃圾混合物中，凡是种过花生、番茄、茄子、烟草、木麻黄、桉树、菊花、大丽花等染病植物的土壤，以及这些罹病植物的花、茎、根和叶的病残体接触过的土肥、水源都有可能存在和繁殖青枯病原细菌，若使用这些土壤、水肥培育美人蕉就会发生青枯病。病菌在土壤中可存活1年以上，干燥或水淹时仅能存活30天和90天。病菌主要从寄主伤口侵入，风雨损伤、昆虫蛀食、人为活动都会为病菌侵入创造机会。地表迳流，株间连根是小区间主要的传播途径。远距离传播靠带病的块茎繁殖材料。一般每年3月开始发病，6~10月发病严重，7~9月为高峰期。台风雨后，当大气温度在33~35℃，相对湿度80%以上时，若绿地积水，青枯病最易流行。 [图片]防治方法： 1.不要在病区取块茎作繁殖材料，严格检疫，发现批量带病种苗，应成批淘汰。 2.不要在发生过青枯病的土壤上种植美人蕉。若要施用土杂肥应先堆沤，充分腐熟，或每平方米用40％福尔马林50倍液6公斤淋洒后复盖薄膜消毒。 3.病害流行期不要中耕除草，避免损伤植株。发现病株立即拔除，挖去病土并在四周撒淋25%青枯灵400~600倍液或90%土、链霉素3000~4000倍液或硫磺粉剂。在病区台风过后最好淋撒上述药剂1次。养殖注意事项：充足的日照，美人蕉喜欢阳光的照射，每天要给予最少6个小时的日光照射，如果缺少阳光将导致花期延后，页面变黄等。合适的温度，美人蕉喜欢温暖的天气，在10度以下将停止生长，零度时就会出现冻害，最适宜的温度在20-26度之间。在冬天时记得防止因天气过冷造成的冻害。及时浇水，美人蕉喜湿润，所以平时要多浇水，特别是夏天天气较热，水分蒸发较快的情况下。但是在冬天和刚栽培的时候要少浇水。移栽第一次浇水时要浇透，平时保持盆图湿润即可，随着植株根茎生长，浇水量可逐步增加。土壤及施肥，美人蕉对土壤不是很挑剔，但最好是疏松、排水良好的土质，另外还要土壤深厚。在种植之前要施足基肥，刚生长的前两个月适合每15天施一次肥料，之后每一个月施肥一次即可。

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Miss Chen

2018年05月26日

柑橘是一种常见的水果，几乎人人都吃过，柑橘树自生活中也比较常见。柑橘树是一种常绿小乔木，四季常青，枝叶整齐茂密，远远看去非常漂亮。春天香花满树开放，秋天黄果挂满枝头，让人垂涎欲滴。柑橘也是我国南方地区的重要经济水果之一，每年柑橘病虫害的发生，都会造成柑橘大幅度减产，果实的品质下降，给果农带来很大的经济损失。 [图片]1柑橘病害的综合防治 1.1农业防治农业防治是最基本、最经济、最安全的病虫害防治措施，是果树无公害病虫综合治理的基础。主要措施有：选用优良的抗病虫品种的脱毒苗木；合理密植和间作，保护天敌，保持生态平衡。及时清除病虫残体，中耕除草，摘除病虫果和虫苞，减少果园内外的病虫初次和再次侵染来源。加强栽培管理，合理施肥，采取果实套袋技术，提高果树对病虫害的抵抗能力。 1.2生物防治许多害虫有其自然的天敌，如食蚜蝇、草蛉、七星瓢虫等以蚜虫为食；赤眼蜂可控制卷叶虫、吹绵蚧；利用大红瓢虫可有效控制柑橘吹绵蚧。通过果园合理间作作物、种植绿肥及有益植物、改善果园生态环境，招引天敌，或人工饲养释放、引进天敌，增加天敌种群数量，恢复其自然控制力，充分利用天敌来杀灭柑橘病虫害。 1.3物理防治即根据果树害虫的习性，采取机械方法防治害虫。常用措施有： 1.3.1捕杀法。在害虫的某一个发育时期，对于有群居性又容易捕杀的害虫，抓住时机进行捕杀。 1.3.2阻隔法。设置屏障，防止幼虫和不善于飞行的成虫扩散、迁移。 1.3.3诱杀法。根据害虫的趋性，采取性引诱剂诱杀、糖醋液诱杀、频振式杀虫灯诱杀，降低虫口密度，减少化学防治次数。 1.4化学防治化学防治虽然具有作用迅速、效果显著、使用方便等优点，但长期广泛使用会使许多病虫产生抗药性，杀伤天敌，污染果品及其环境，对人们的健康和可持续发展造成威胁。因此，必须注意选择农药品种，改进技术。达到经济、有效、安全的目的。在使用化学方法防治柑橘病虫害时应注意：①严格执行农药品种的使用准则，禁用高毒、高残留、高致病农药，有节制地使用中毒低残留农药，优先采用低毒低残留或无污染农药。②科学使用农药。严格执行安全用药标准，通过对症下药、选择作用机理不同的几种农药，交替使用来提高防治效果。 2柑橘病害防治技术 2.1柑橘疮痂病病状：柑橘疮痂病又称“疥疮疤”、“癞头疤”、“麻壳”等，主要为害叶片、新梢和果实，尤其易侵染幼嫩组织。叶片染病，开始产生蜡黄色油渍状小斑点，然后病斑渐扩大、木栓化，形成灰白色至暗褐色圆锥状疮痂，病斑一面突出，一面凹陷。严重时病斑连片，导致叶片扭曲畸形。幼叶染病常干枯脱落；幼果染病，果面密生茶褐色疮痂，常早期脱落。防治方法：对外来苗木实行严格检疫或将新苗木用50%多菌灵可湿性粉剂800倍液浸泡30min。当春芽长1～2mm时喷40%多菌灵胶悬剂600倍液或70%甲基硫菌灵超微可湿性粉剂1000倍液，等有2/3左右的花落掉后再喷上述杀菌剂，温带桔区于5月下旬至6月上旬补喷1次。 2.2柑橘溃疡病病状：主要为害叶片、果实和枝梢。叶片染病，初期在叶背产生黄色或暗黄绿色油渍状小斑点，然后叶面隆起，出现米黄色海绵状物。果实染病，与叶片上症状相似。高感品种枝梢也染病，初生圆形水渍状小点，后扩大，病斑木栓化，形成大而深的裂口。最后数个病斑融合形成黄褐色不规则形大斑，边缘明显。防治方法：在无病区设置苗圃，对所用的苗木和接穗用72%农用链霉素可溶性粉剂1000倍液加1%酒精浸30～60min，或用0.3%硫酸亚铁浸泡10min进行消毒。落花后开始喷洒1∶1∶200倍式波尔多液或70%甲基硫菌灵超微可湿性粉剂1000倍液，幼龄树在春梢、夏梢、秋梢萌发后20d各再喷1次。 2.3柑橘炭疽病病状：柑橘炭疽病俗称爆皮病，叶片染病多发生在叶缘或叶端，病斑浅灰色，边缘褐色，呈不规则形或近圆形，直径0.2～1.4cm。枝梢染病始于叶柄基部腋芽处，病斑开始呈淡褐色，椭圆形至长梭形，病部环枝一周时，病部以上变成灰白色枯死并散生小黑点。大枝或主干染病，病斑长椭圆形或条状，果实染病上面常出现干斑或果腐。防治方法：冬季清园时喷1次波美0.8～1度石硫合剂，在春梢、夏梢、秋梢及嫩叶期、幼果期喷0.5∶1∶100倍式波尔多液或80%炭疽福美可湿性粉剂800倍液。 2.4柑橘树脂病病状：柑橘树脂病又称砂皮病、蒂腐病。桔树染病后致枝叶凋萎或整株枯死。枝干染病时，表现流胶和干枯两种类型。流胶型：病部初呈灰褐色水渍状，组织松软，皮层具细小裂缝，后流有褐色胶液，边缘皮层干枯或坏死翅起，使木质部裸露。干枯型：皮层初呈红褐色、干枯稍凹陷，有裂缝、皮层不易脱落，发病部位和健康部位相接处有明显隆起界线，流胶不明显。发病树皮下有黑色小粒点。叶片染病，表面散生黑褐色硬质突起小点，有的很多密集成片，呈砂皮状。成熟果实染病，果蒂附近最初出现水渍状，并变软，后变深褐色波及到脐部，最终导致全果腐烂。防治方法：剪除病枝，收集落叶，集中烧毁或深埋，刮除病枝或病干上病皮，病部伤口涂36%甲基硫菌灵悬浮剂100倍液，施药后再用无色透明的乙烯薄膜包扎伤口，结合防治炭疽病、疮痂病喷洒70%甲基硫菌灵超微可湿性粉剂1000倍液或60%防霉宝可湿性粉剂800倍液。 [图片]2.5柑橘脚腐病病状：柑橘脚腐病俗称“烂蔸巴”。主要为害根颈部，地上部也可受害。根颈部染病初期，病部褐色，有酒糟气味，流有胶液。严重的环绕整个树干，使柑橘树死亡。防治方法：发现病树，及时将腐烂皮层刮除，并刮掉病部周围健全组织0.5～1cm，然后在切口处涂抹10%等量式波尔多液或2%～3%硫酸铜液。 2.6柑橘煤污病病状：柑橘煤污病又称煤烟病，主要为害叶片、枝梢及果实，初期仅在病部生一层暗褐色小霉点，然后逐渐扩大，直至形成绒毛状黑色或暗褐色霉层，并散生黑色小点。防治方法：及时防治介壳虫、粉虱、蚜虫等刺吸式口器害虫，发病初期喷40%克菌丹可湿性粉剂400倍液或0.5∶1∶100倍式波尔多液。 2.7柑橘立枯病病状：柑橘立枯病有两种，一种是丝核菌引起的真菌病害，另一种是由拟细菌引起的立枯病。丝核菌立枯病：茎部及根茎近地面处，一开始出现褐色水渍状斑块，后逐渐扩大，使病部缢缩或叶片自上向下萎蔫死亡，病部可见白色菌丝休，后期可见灰白色油菜籽状小菌核。拟细菌立枯病：叶脉先黄化，后叶肉萎黄，病叶硬化向外卷，叶脉隆起或破坏，逐渐木栓化，造成落叶或枯梢，，新生叶细小，色淡萎黄，病株开花提前，但易落。果实小或畸形，树势弱，2～4年后枯萎死亡。防治方法：合理轮作，避免连作，每平方米苗床施用25%甲霜灵可湿性粉剂9g＋70%代森锰锌可湿性粉剂1g对细土4～5kg拌匀，施药前打透底水，取1/3拌好的药土撒于地下，其余2/3药土覆在种子上面。发病初期喷20%甲基立枯磷乳油1200倍液或75%百菌清可湿性粉剂600倍液。对拟细菌引起的立枯病从两方面入手，一是喷洒25%扑虱灵可湿性粉剂1500倍液或50%抗蚜威超微可湿性粉剂3000倍液防治柑橘木虱。二是喷盐酸土霉素500～1000mg/L溶液。 2.8柑橘黑星病柑橘黑星病又称黑斑病。主要为害果实，也可为害叶片、枝梢。果实染病分为黑星型和黑斑型两种类型。黑星型病状：病斑红褐色，圆形，直径1～6mm，后期病斑变成黑褐色，边缘隆起，中部凹陷，上面着生黑色小粒点，贮藏期继续扩展，发病部位易被腐生菌侵染引起腐烂。黑斑型病状：病斑大，淡黄色或橙黄色，后渐变成暗褐色至黑褐色，圆形或不规则形，严重时病斑连片覆盖大部分果面。贮藏期，果肉变黑，腐烂。防治方法：秋末冬初结合修剪，剪除病枝、病叶，并清除地上落叶、落果，集中销毁。同时喷洒1～2波美度石硫合剂，柑橘落花后喷洒0.5∶1∶100倍式波尔多液或50%多霉灵可湿性粉剂1500倍液，每隔15d喷1次，连续防治3～4次。 2.9柑橘黑腐病病状：主要为害果实。症状常因品种而稍有不同。温州蜜柑染病，果面近脐部变黄，看上去类似于成熟果，后发病部位变褐，呈水渍状，不断扩大，呈不规则形，四周紫褐色，中央色淡。宽皮桔类，病菌主要从脐部小孔或伤口侵入，致病部果皮呈水渍状，失去光泽，后变黄褐色，果心变墨绿色，具有霉状物。防治方法：剪除过密枝条和枯枝，及时防虫，减少人为伤口和虫伤。发病初期喷洒75%百菌清可湿性粉剂600～800倍液或70%代森锰锌干悬粉500倍液。

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Miss Chen

2018年05月26日

榕树生长迅速，且寿命长，树冠大易成型，且虫害少，是良好的绿化树种。晋人嵇含在《南方草木》中写道：榕树……叶如木麻，实如冬青，树干攀曲，其阴十亩，故人以息焉；而又枝条目口繁、叶又茂细，软条如藤，垂下渐渐入地，藤稍人工，便生根节，或一大株，有根四五条，而横枝及邻树连理。可见榕树易栽，易活，易培养。在300多种各类园林绿化、行道树中，榕树是人们常见与熟悉的树种，约占30%左右。近十年来，榕树更成为园林绿化的宠儿，随处都可看见它的倩影。 [图片]但榕树害虫却给您带来不愉快的心情。当您漫步在行人道上，抬头一望，榕树的叶片斑白缺刻、扭曲畸形，悬吊的毛虫更令您毛骨悚然。这都是榕树害虫所为。下面介绍几种榕树主要害虫的形态及防治方法：一、灰白蚕蛾，属鳞翅目家蚕蛾科形态与习性：成虫、幼虫外表与家蚕相似，但体形较小，成虫体灰褐色，前翅有4条暗褐色线纹，翅中央有半月形黑纹。幼虫体灰白色。卵扁园形，初呈黄色，后变淡黑色。蛹淡黄色，肾披白色丝织状物，以蛹越冬。广州1月底至2月初可见羽化成虫，卵产于枝干上或叶面和叶背上，呈双行排列，初孵幼虫在叶片上取食叶肉残留表皮，随着虫龄增大，幼虫沿叶缘取食，好似家蚕取食一样，幼虫有叶丝悬挂习性。防治方法：由于行道树人流量大，应采用高效低毒、少污染、低臭味的药剂喷杀，掌握初孵幼虫用含100亿以上孢子/克的生物制剂杀螟杆菌1000倍液；或在幼虫孵化盛期用80%敌敌畏乳油1000倍液、90%敌百虫1000倍液喷杀，效果可达90%以上。 [图片]二、榕紫蝶，属鳞翅目斑蝶科形态与习性：成虫翅长75mm体翅暗褐色，反光时呈现紫蓝色光彩，前翅外缘和亚外缘有两列白色斑点，翅反面的前后翅中室各有一白园斑点，环绕后翅中室也有5个白色斑点。卵为顶端球状的园柱形，表面具六边形的图案纹，黄色，近孵化时褐色。老熟幼虫头黑褐色，体背面具褐、白相间的环节，中、后胸和第2、8腹节各有1对紫色内质丝。蛹呈椭园状、光滑，表面具银色金属光彩并有褐色斑纹。该虫在广州4?11月均有发生为害。成虫多在白天活动，卵散产于叶面或叶背，初孵幼虫常将卵壳当第一餐，随后蚕食叶表皮，高龄幼虫沿叶缘咬食成缺刻，严重时把叶片吃光，除为害榕树外，还为害夹竹桃花卉。防治方法：蛹悬挂于枝叶上易发现，可人工摘除集中消灭；低龄幼虫期及时用90%敌百虫1000倍液或80%敌敌畏乳油800倍液喷杀亦可用生物制剂，每克含活孢子100亿以上的青虫菌或苏云金杆菌兑水500?1000倍喷杀，每隔10?15天喷杀一次，连续三次。三、透翅毒蛾，属鳞翅目、毒蛾科形态与习性：雄成虫触角棕色，前翅透明，翅脉黑棕色，翅基黑褐色，后翅黑褐色，顶角透明；雌成虫触角淡黄色，前后翅淡黄色，前翅中室后缘散布褐色鳞片。卵赤色。幼虫暗色，第1?2腹节背面有茶褐色大毛丝，各节皆有3对赤色肉质隆起，丛生长毛，背线黄色，老熟幼虫水青色，雄背线为暗黑色。蛹略呈纺锤形，有红褐色斑。该虫在广州5?10月间发生，以5?6月最为普遍，为害最烈。幼虫咬食叶片，造成叶片残缺不全，严重影响生长。防治方法：幼虫期喷90%敌百虫800倍液或兴棉宝3000倍液，亦可采用生物制剂苏云金杆菌和核型多角病毒以毒杀幼虫。发生少量时可采用人工捕杀幼虫和蛹。四、榕管蓟马，属缨翅目，管蓟马科形态与习性：虫体黑褐色，头顶单眼区有锥状突起和六角形网纹，前翅透明，前后翅缘呈平行状，前足胫节黄色，中、后足胫节为褐色，腹部尾端管状，卵呈肾形乳白色。该虫在广州全年发生，最为普遍，为害严重。成虫、若虫均为害嫩叶和幼芽，受害叶子形成虫瘿，出现叶片、嫩梢卷缩畸形，害虫藏匿其中，受害部位颜色变为深紫红色。除为害榕树之外，亦为害杜鹃、龙船花等。防治方法：发生高峰期喷2.5%鱼藤精300倍液；80%敌敌畏800倍或2.5%敌杀死乳油剂3000倍液喷杀，每隔7?10天一次，连续3次防效显著。

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Miss Chen

2018年05月26日

听到发财树这个名字，男女老少都喜欢养，特别是做生意的人喜欢，还有很多公司开业的时候，都喜欢送发财树，毕竟发财树寓意是发财。发财树属于盆栽植物，其实不是很好养，随处可见被养死了的发财树，只有把发财树茂盛，才能够体现出发财树的价值和含义，下面来看看发财树在养殖过程中常见的病害都有哪些，该如何防治。 [图片]发财树常见的病害有根（茎）腐病与叶枯病。一、根（茎）腐病这是一种严重危害发财树的常见病害，又称为腐烂病。防治方法：（1）保持栽培环境的干爽，重视栽培介质及场地的消毒；（2）半成品出柜卸至操作棚后，即用速克灵喷洒发财树头部，以预防灰霉病菌的危害；（3）栽种前用利刀剪除主根顶部扭伤及腐烂组织，然后再用速克灵喷洒伤口，晾干后即栽植；（4）栽植一周后，盆中的介质渐干，愈合组织已形成，新根已开始长出，用普力克、安克或锌锰灭达乐（雷多米尔-锰锌）喷洒发财树光杆，以药液沿杆部流入盆土为宜。此后的杀菌剂以安克、土菌灵、雷多米尔或疫霜灵每周一次轮用；（5）若腐霉病菌活跃，则用普力克、土菌灵、雷多米尔或疫霜灵喷施，一般药效在两周左右。若天气仍然不好，须再用不同的药剂喷施，以防抗药性的产生。期间若发现有溃烂植株，应立即丢弃。 [图片]二、叶枯病防治方法：（1）发现病叶及时摘除，并销毁；（2）在发财树的栽培过程中应加强养护管理，适时浇水施肥，每个生长季节可追施肥2-3次叶面肥，如0.5%的氮磷酸二氢钾或双效微肥的200倍液；（3）苗木从南方向北方调运之前，叶面喷施保护性杀菌剂，如70%百菌清800倍液，或者18%多菌铜乳粉200倍液，或50%退菌特600倍液，运到北方后，应及时定植，加强肥水管理，防止脱水和脱肥。南方地区栽培发财树可从雨季开始，每隔10-15天喷施50%多菌灵800倍液，或70%百菌清800倍液，75%甲基托布津1500倍液。另外，虫害主要有蔗扁蛾，该虫在我国是新纪录，主要是幼虫危害发财树，还可对一品红、福禄桐、鹅掌木、夏威夷椰子进行危害。

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